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Ask Well: Do Mosquitoes Spread Ebola?

Q

Do mosquitoes spread Ebola in Africa?

Reader Question • 112 votes

A

No. Africa has plenty of mosquitoes, and plenty of diseases spread by mosquitoes, but Ebola is not one of them.

To understand why mosquitoes are not carriers of Ebola, it is important to understand how mosquitoes bite. Only female mosquitoes bite, and they do not fly from person to person, biting one after another. They only hunt for blood when they plan to lay eggs. (At other times, female mosquitoes, like male mosquitoes, live on sugary plant nectar).

When a mosquito sucks blood, the insect’s abdomen swells up, and the mosquito immediately finds rest on a wall or tree for hours or days to digest the blood and let it nourish her eggs. Then the mosquito flies around seeking water in which to lay the eggs. Only after laying the eggs does the mosquito look for another meal.

All mosquito-borne diseases — malaria, yellow fever, West Nile virus, dengue fever, chikungunya and elephantiasis, for example — have slowly merged into this feeding cycle through evolution. Mosquitoes are not born with these diseases. A mosquito must pick up a disease from a human, and then the disease has to survive the digestive process and get into position to infect the next human. In the case of malaria, which kills more than 600,000 people every year, the parasites in the blood stored in the mosquito’s gut spend up to two weeks changing into five different forms. Two of those forms “mate," creating a final form that migrates through the mosquito to end up in her salivary glands.

When mosquitoes bites, they inject saliva, which contains anticoagulants so they don’t get clots in the thin proboscis — the straw they have in place of a mouth — that they insert into you. Ebola can’t get into mosquito saliva, so mosquitoes don’t transmit it.